Re: [PATCH net-next 3/5] drivers/net/phy: add connection between ethtool and phylib for PLCA

On Thu, Jan 05, 2023 at 11:49:18AM +0100, Piergiorgio Beruto wrote:

On Thu, Jan 05, 2023 at 11:03:46AM +0200, Leon Romanovsky wrote:

quoted

On Wed, Jan 04, 2023 at 03:06:30PM +0100, Piergiorgio Beruto wrote:

quoted

This patch adds the required connection between netlink ethtool and
phylib to resolve PLCA get/set config and get status messages.

Signed-off-by: Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
---
 drivers/net/phy/phy.c        | 172 +++++++++++++++++++++++++++++++++++
 drivers/net/phy/phy_device.c |   3 +
 include/linux/phy.h          |   7 ++
 3 files changed, 182 insertions(+)

<...>

quoted

+	curr_plca_cfg = kmalloc(sizeof(*curr_plca_cfg), GFP_KERNEL);
+	if (unlikely(!curr_plca_cfg)) {

Please don't put likely/unlikely on kamlloc and/or in in control path
flow.

Fixed. Although, I am curious to know why exactly it is bad to
linkely/unlikely on kmalloc. Is this because if we're in a situation of
low memory we don't want to put more "stress" on the system failing
branch predictions?

likely/unlikely is helpful when you are sure that compiler won't be able
to guess the right flow and probably will get it wrong. It is usually not
the case for any "return to error" flows and sure not the case here.

Bottom line, you won't see any difference in assembly if you put or
remove unlikely keyword.

Thanks

quoted

Thanks